Coupling of Energy Metabolism and Synaptic Transmission at the Transcriptional Level: Role of Nuclear Respiratory Factor 1 in Regulating both CytochromecOxidase and NMDA Glutamate Receptor Subunit Genes

Abstract

Neuronal activity and energy metabolism are tightly coupled processes. Regions high in neuronal activity, especially of the glutamatergic type, have high levels of cytochrome c oxidase (COX). Perturbations in neuronal activity affect the expressions of COX and glutamatergic NMDA receptor subunit 1 (NR1). The present study sought to test our hypothesis that the coupling extends to the transcriptional level, whereby NR1 and possibly other NR subunits and COX are coregulated by the same transcription factor, nuclear respiratory factor 1 (NRF-1), which regulates all COX subunit genes. By means of multiple approaches, including in silico analysis, electrophoretic mobility shift and supershift assays, in vivo chromatin immunoprecipitation, promoter mutations, and real-time quantitative PCR, NRF-1 was found to functionally bind to the promoters of Grin 1 (NR1), Grin 2b (NR2b) and COX subunit genes, but not of Grin2a and Grin3a genes. These transcripts were upregulated by KCl and downregulated by tetrodotoxin (TTX) in cultured primary neurons. However, silencing of NRF-1 with small interference RNA blocked the upregulation of Grin1, Grin2b, and COX induced by KCl, and overexpression of NRF-1 rescued these transcripts that were suppressed by TTX. NRF-1 binding sites on Grin1 and Grin2b genes are also highly conserved among mice, rats, and humans. Thus, NRF-1 is an essential transcription factor critical in the coregulation of NR1, NR2b, and COX, and coupling exists at the transcriptional level to ensure coordinated expressions of proteins important for synaptic transmission and energy metabolism.

Mitochondrial Amyloid-β Levels are Associated with the Extent of Mitochondrial Dysfunction in Different Brain Regions and the Degree of Cognitive Impairment in Alzheimer's Transgenic Mice

“…Synaptic contacts decrease with normal brain aging and this is associated with decreased COX activity [56]. This may reflect the tight coupling between synaptic and mitochondrial function at the transcriptional level with both COX and NMDA glutamate receptor genes being activated by the transcription factor nuclear respiratory factor 1 (NRF-1) [57]. Together these data indicate that the decreased COX activity from normal aging coupled with the inhibition by Aβ may lead to the synaptic deficits observed in AD.…”

Bioenergy sensing in the brain

“…Its importance in neural tissue is especially exceptional, given that the brain is the most energy-demanding organ in the body and is therefore the most vulnerable to energy disregulation and depletion. 111 AMPK is critically involved in multiple developmental stages and functionality of neurons, including migration, maturation, glucose uptake and metabolism and neuronal communication, including synaptic transmission 112 and plasticity. 113 At a system level, AMPK localized in energy-sensing neurons and circuits in the hypothalamus is responsible for the control of feeding behavior by incorporating peripheral energy-related signals.…”

Transcriptional Regulation of Brain-derived Neurotrophic Factor Coding Exon IX

“…Each promoter construct was transfected into N2a cells using Lipofectamine 2000 (Invitrogen). Each well received 0.6 g of reporter construct and 0.06 g of pRL-TK Renilla luciferase vector (68). Firefly luciferase and Renilla luciferase activities were measured sequentially using the Dual Luciferase Reporter Assay System (Promega).…”

“…Primary neurons transfected with shRNA against NRF-2␣ were further stimulated with KCl. A final concentration of 20 mM KCl was added to the culture medium for 5 h according to our published method (68). After this period, cells were harvested for RNA and protein isolation.…”

“…Either 2 g of NRF-2 overexpression vector, or 1.5 g of the pcDNA3.1 empty vector and 0.5 g of TurboGFP vector for green fluorescence were used for primary neuronal cultures. Transfected primary neurons were blocked for 3 days with TTX at a final concentration of 0.4 M and starting on the day after transfection as previously described (68). Two to 4 days after transfection, neurons were harvested for RNA and protein isolation.…”